Hydrologic indicators of hydraulic conditions that drive flow–biota relationships

Figures & data

Fig. 1 Nineteen study reaches located in the Thomson, Broken, Goulburn and Loddon river catchments, Victoria, Australia (see Table 1 for site details).

Table 1 Site characteristics: cross-sections, reach length, valley confinement and Köppen climate region.

Region	River	Code	Site	No. of cross-sections	Reach length (m)	MrVBF	Valley confinement^(a)	Köppen climate region^(b)	Stream gradient	Bankfull depth (m)	Bankfull width (m)	Streamflow series length (unit)
South	Thomson	Thom1	Thomson River at The Narrows	11	285	3.9	1	3	0.004 67	3.4	27.5	1955–1998
		Thom2	Thomson River at Upstream of Cowwarr Weir	12	460	4.8	2	6	0.006 12	3.8	28
		Thom6	Thomson River at Bandalaguah	6	279	6.6	3	6	0.000 49	7.3	40.9
		Thom3	Old Thomson River Annabranch at Heyfield	10	367	4	1	6	0.000 94	4.9	32.3
		Thom5	Thomson River at Wandocka	12	647	6.6	3	6	0.000 69	5.4	29.7
		Thom4	Rainbow Cr Annabranch at Heyfield	10	417	5.7	2	6	0.002 21	4.8	120.6
Central	Loddon	Lodd3	Tullaroop Creek, downstream of Tullaroop Reservoir	12	561	6.7	3	6	0.000 89	6	44.2	1974–2000
		Lodd2	Loddon River, downstream of Cairn Curran Reservoir	8	388	6.7	3	6	0.000 85	4.8	34.4
		Lodd1	Loddon River, downstream of Laanecoorie Reservoir	10	675	6.5	3	12	0.000 23	7.6	55.8
		Lodd6	Loddon River, downstream of Serpentine Weir	10	528	6.6	3	12	0.000 23	9	50.6
		Lodd5	Loddon River at Appin South	10	551	7.7	3	12	0.000 19	3.2	23.2
North	Goulburn	Goul1	Goulburn River at Alexandra	17	3000	3.2	1	6	0.000 67	3.9	56.4	1975–2000
		Goul2	Goulburn River at Ghin Ghin	18	3000	4	1	6	0.000 54	5.2	76
		Goul3	Goulburn River at Northwood	16	3000	5.7	2	6	0.000 33	6.5	74.4
		Goul4	Goulburn River at Murchison	8	2800	6.7	3	9	0.000 33	9.4	91.8
		Goul5	Goulburn River at Wyuna	9	4240	8	3	6	0.000 11	9.2	74.6
North	Broken	Brok1	Broken River at Swanpool Rd	17	1067	4.7	2	6	0.004 93	4.6	32.5	1975–2000
		Brok2	Broken River at Riverview Drive	15	946	5.8	2	9	0.000 64	4	26.7
		Brok3	Broken River at Goomalibee Rd	17	1041	6.7	3	9	0.000 05	4.2	38.4

Notes ^(a)Valley confinement: Valley Bottom Flatness Measure (MrVBF) categories defined by Turner (2009)—1: Upland, MrVBF = 0–4.49; 2: Midland, MrVBF = 4.5–5.99; and 3: Lowland, MrVBF > 6.^(b)Köppen climate region (see Peel et al. 2007 for definitions)—3: Temperate, No dry season (mild summer); 6: Temperate, No dry season (warm summer); 9: Temperate, No dry season (hot summer); 12: Grassland, Warm (persistently dry).

Table 2 Streamflow statistics. All statistics underwent LN transformation unless otherwise noted (SQRT: square-root transformation; UT: untransformed).

Code^(a)	Variable name	Code^(a)	Variable name
MA24–MA35	Variability in monthly flows (SQRT: MA24, MA25, MA28)	FL3	Frequency of low-flow spells
MA10	Spread in daily flows	FL2	Variability in low flood pulse (SQRT)
ML14	Mean of annual minimum flows	FH6	Flood frequency (using upper thresholds of 3 times median flow) (SQRT)
ML16	Median of annual minimum flows (SQRT)	FH7	Flood frequency (using upper thresholds of 7 times median flow) (SQRT)
MH26	High peak flow	DL17	Variability in low-flow pulse duration (SQRT)
MH1	Mean maximum monthly flows	DH16	Variability in high-flow duration
MH2–MH12	Mean maximum monthly flows (SQRT: MH5, MH6)	DL6	Variability in annual minima of one/3/7/30/90 day means of Daily Q
MH14	Median of annual maximum flows	DL10	Variability in annual minima of one/3/7/30/90 day means of Daily Q
RA6	Change of flow	RA9	Variability in reversals
DH13	Means of 1-/7-/30-day minima of daily Q	RA7	Change of flow (Untransformed)

Notes See Olden and Poff (2003) for full definition. For consistency the same name abbreviations have been used in this article. Groups of monthly statistics (e.g. M_A24–M_A35) represent January (M_A24) to December (M_A35).

^(a)M: Magnitude; D: Duration; F: Frequency; R: Rate of change; A: Average flow conditions; L: Low-flow conditions; H: High-flow conditions.

Table 3 Principal component analysis.

		PCI	PCII	PCIII	PCIV	PCV
Natural	Cumulative variance (%)	45	63	74	80	85
	Strongly correlated statistics	MH2	MA30	MH8	MA27	ML16
Alteration	Cumulative variance (%)	41	57	69	77	82
	Strongly correlated statistics	MA10	MH11	MH8	DL6	DL10

Notes M_H2: mean maximum monthly (January); M_A30: variability of monthly flows (July); M_H8: mean maximum monthly flows (August); M_L16: median of annual minimum flows; M_A27: coefficient of variation of monthly flows (April); D_L10: variability of annual minima (1- and 7-day).

Fig. 2 Area of bench inundation, Froude number, area of shallow water and area of deep water as a function of discharge in each survey reach of the Broken, Thomson, Loddon and Goulburn river systems.

Fig. 3 Area of bench inundation, Froude number, area of shallow water and area of deep water as a function of discharge in each survey reach for lowland, midland and upland rivers.

Fig. 4 Regression models for modelled vs calculated hydraulic features: (a) natural streamflow conditions and (b) alteration in streamflow statistics and hydraulic features. Symbols: × upland, ◊ midland and ☐ lowland sites.

Table 4 Regression models, adjusted R² and standard error of estimates for each hydraulic metric in the ‘natural’ and ‘alteration’ data sets.

Data set	Habitat parameter	Regression equation	Adjusted R^2	Standard error of estimates
Natural
	Deep	=(0.178 × N_MH2) + (0.414 × N_MH8) + (3.782 × ML16) – 3.282	0.82	0.29
	Bench	=(0.838 × N_MH2) – 5.031	0.69	0.88
	Shall	=(–0.670 × N_MH8) – 2.990	0.23	0.68
	Fr	=(–0.097 × N_MA27) + 0.306	0.21	0.13
Alteration
	Deep	=(0.221 × C_MA10) + (0.399 × C_MH11) – 0.113	0.53	0.13
	Bench	=(0.434 × C_MA10) + (0.304 × C_DL6) – 0.191	0.50	0.28
	Shall	No Model
	Fr	No Model

Turner, M., 2009. Natural spatial and temporal hydraulic habtiat variability; Implications for regional environmental flow planning. Thesis (PhD). Department of Civil Engineering, Monash University.

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Peel, M.C., Finlayson, B.L., and McMahon, T., 2007. Updated world map of the Köppen-Geiger climate classification. Hydrology and Earth System Sciences, 11, 1633–1644. doi:10.5194/hess-11-1633-2007.

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Olden, J.D. and Poff, N.L., 2003. Redundancy and the choice of hydrologic indices for characterizing streamflow regimes. River Research and Applications, 19 (2), 101–121. doi:10.1002/rra.700.

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